In the production of tobacco in finished product forms, especially smoking tobacco, the tobacco leaves, after harvesting, can be subjected to a fermentation or curing process which involves the degradation of organic structures within the leaf. These degradation processes begin during the drying of the tobacco and ultimately terminate.
The endothermic fermentation and curing processes which have been used heretofore, generally treat the tabacco in bales or in stacks or other accumulations of leaves on special carriages in closed chambers. The atmosphere in the chamber is ambient air and both the temperature and the moisture content of this atmosphere are controlled to regulate the fermentation process. In conventional endothermic fermentation or curing processes, as in the present case, the relative humidity in the chamber is generally held between 55% and 80% while the temperature is maintained between 30.degree. C. and 60.degree. C.
The endothermic fermentation process is significantly faster than natural fermentation although it too can require up to about six weeks.
Even after conventional fermentation processes, the tobacco contains relatively large proportions of nicotine and condensates.